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Open Access Original Article Issue
Impact of micro-scale characteristics of shale reservoirs on gas depletion behavior: A microscale discrete model
Advances in Geo-Energy Research 2025, 15(2): 143-157
Published: 02 January 2025
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Shale gas has become increasingly significant in the global energy supply. Mineral heterogeneity in shales importantly impacts gas transport within the shale matrix and therefore the depletion history curve. A microscale discrete coupling model is introduced to clarify mass transfer and mechanical interactions, as well as their impact on gas transport properties, ranging from individual mineral through ensemble field scale. The model uses a mineral morphology thin-section obtained through tescan integrated mineral analyzer with the mechanical parameters, controlling both elastic and viscosity behavior of each mineral, achieved through nanoindentation. A coupled model for poromechanical evolution is proposed and solved using COMSOL. The applicability of the model results are validated against field data using a dimensionless approach. This confirms that in the early stages of gas depletion, gas is primarily liberated from inorganic minerals, whereas in later stages, it is predominantly sourced from adsorbed gas from the organic matter. Over time, the permeability of the inorganic minerals decreases, and a higher Young’s modulus of the minerals results in a greater ultimate permeability ratio. Evolution of the effective diffusion coefficient for the organic matter is controlled by multiple components. A negative correlation exists between mineral grain size and the creep effects, indicating that larger grain sizes result in smaller creep magnitudes during gas production. The Young’s modulus of inorganic matter is inversely correlated with the diffusion coefficient, while an increase in the Young’s modulus in the organic matter corresponds to a higher diffusion coefficient. The proposed model complements the traditional continuum dual-medium method and provides a clearer understanding of the interactions between minerals during gas depletion behavior.

Open Access Editorial Issue
Advances in in-situ modified mining by fluidization and in unconventional geomechanics
Advances in Geo-Energy Research 2021, 5(1): 1-4
Published: 16 November 2020
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Increasing large-scale development and utilization of new geo-energy sources and geo-resources heralds the need for worldwide implementation of sustainable development. The extreme complexity in recovery conditions, including ultra-low-permeability reservoirs, low-energy-density reserves and high temperatures and high pressures, defines a challenge in efficiently recovering such energy, fuel and mineral resources. Hence, development of efficient mining methods and the related determination of geo-mechanical properties of reservoirs remains a key topical issue. During the simultaneous 2 nd International Symposium on In-situ modification of Deposit Properties for Improving Mining and the 7 th Unconventional Geomechanics Symposium, held both in person and online from November 7-8, 2020, a broad array of advances in the science and technology of geo-energy and geo-resource recovery were presented. The symposia were attended by more than 200 participants from China, USA, Canada, UK, Australia, Japan, Singapore, and Turkey. Twenty-four invited talks were presented, seven of which were online, four of which were pre-recorded, and thirteen of which were in person. Twenty-two general talks were held in two parallel sessions. Participants interact freely through both online and in-person speakers. These interactions will enable future collaborations.

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